Yamaha XZ 550
From Yamaha Wiki
|Engine||552 cc, 4-stroke, V-Twin, liquid-cooled, DOHC|
|Weight||(Dry weight (motorcycle)), 212 kg (467 lb) (Wet weight (motorcycle))|
The Yamaha Vision (XZ550) was a motorcycle produced in 1982-83. It offered innovative technology in its motor and bold styling.
Three slightly different models were produced: the European model, with dual front braking discs, the 1982 US model (RJ), with a single disc and the 1983 US model (RK), with dual discs and a fairing. The models also use different sparkplugs and front forks. The Vision was the first Yamaha model to feature automotive-style downdraft carburetors with the air cleaner box mounted atop the carburetors, as opposed to most motorcycles' sidedraft carburetors with their side-mounted air cleaners. While downdraft carburetors flow air into the engine more efficiently than sidedraft carburetors, the height of the carburetors and their airbox required Yamaha to design a large tunnel into the bottom of the gas tank. While the tank holds slightly over five gallons of fuel, it looks much larger thanks to the tunnel and suggests that the bike is top-heavy--which it is not.
The Vision has a water-cooled engine. At the time, most water-cooled motorcycle engines had fins, intended to suggest the cooling fins on aircooled engines, cast into their cylinder heads. While fins are absolutely necessary on an aircooled engine--they increase the surface area of the head, hence improve cooling--they serve no function on a water-cooled engine. By leaving the fins off the Vision's engine, it simplified the engine's manufacturing process, reduced the amount of metal needed to make the cylinders, and lowered the cost of the engine without affecting its functionality.
The Yamaha Vision was originally conceived in the late 1970s when motorcycling was at its peak, and spent three years in development, being overseen by a small group of designers and enthusiasts rather than "committee think". The stated aim was to produce "a touring bike of the highest calibre, its touring credentials matched by awesome sporting performance." The Vision succeeded on both fronts, its comfort on long rides and veritable torque-monster engine matched by its distinctive deep V-Twin exhaust beat and "neck-snapping performance." The bike was considered "rather B.M.W.-like," in reference to its touring credentials, and "the most European motorcycle from Japan in recent memory."
Unfortunately, producing an entirely new product from scratch is never without initial problems, and the Vision suffered from a few. An off-idle carburetion quirk, known as the "Vision stumble", meant the first year machines were prone to initial stuttering on part and full-throttle takeoff. The "Vision stumble" problem, after months of research, was finally solved by racer Marc Salvisberg, who later started Factory Pro Tuning. The problem, it seemed, wasn't a Yamaha development problem at all, but was actually a lean spot, just off idle, caused by what appeared to be residual casting sand that filled the "off-idle" bleed holes at the throttle butterfly plate in the "Weber style" Mikuni carb. That information was immediately relayed to Yamaha US, where it was relayed to Japan and verified. The 1983 models carbureted, essentially flawlessly.
In the 1982 model, lightning quick steering was considered too extreme for some, though was highly appreciated by sporting riders. The weight distribution was 55/45 and the lightly loaded front end benefited from the installation of a slightly larger than usual front tire. The front suspension was described as too soft, the rear, even with an adjustable shock, difficult to dial in. On the electrical side, the Vision had "a well deserved reputation for eating starters and stators."
The 1983 model Vision fixed most of the faults, with an "improved" carburetor eliminating the "stumble," air adjustable front forks firming up the ride and improving the roadholding. A full fairing, with adjustable hot and cold air vents, effectively shielded the rider. With the improved carburetor and minor internal adjustments, the engine's strengths became apparent: it had enormous torque at all revs, and would pull from idle in top gear. Despite the 10,000 R.P.M. redline, the oversquare bore and short stroke kept the piston speed low, with the result that the engine always sounded relaxed, even at peak revs. The exhaust note has been compared to that of a Ferrari Testarossa (which came out several years later.) With its unique "hang support" frame, whereby the engine is suspended beneath the frame for lighter weight, the Vision's performance and roadholding were far ahead of its time. Unfortunately, so too was the cost. The motorcycling boom of the Seventies was already receding before the Vision hit the showroom floors, and rival motorcycle companies offered cheaper motorcycles without the quirks. The model was discontinued in 1983, though it maintains cult status online. In current times, the Vision has been found to be one of the easiest motorcycles to modify to the owner's personal taste. There are "bobbers" , full touring bikes, cafe racers ,and general sport bikes in all areas of the world. The online forum for the Vision ,www.ridersofvision.net, is a very informative and most complete location for finding repair information,rider help,ride reports and information known to this date.
The XZ550 was also released in a 400cc version from 1983 to 1987 that was visually almost identical to the 550, although it has sightly different height, width, length and weight specifications. It was sold, in full faired, half faired and naked versions. The XZ400 was sold into non-US markets (including Europe, Japan, Australia and New Zealand). The most obvious differences other than engine capacity were slotted disk brake rotors, and a strap on the seat. Most parts are interchangeable, although the 400 had a different bore and stroke, valve sizes and final gearing, making engine part swaps difficult.
see also- xz550.com
- 4 stroke 70-degree DOHC V-Twin
- 4 valves per cylinder
- liquid cooled
- 552 cm³
- 65 hp (48 kW) @ 9500 rpm
- 50 N·m (37 ft·lbf) @ 8500 rpm
|Model Designation:||XZ 550 RJ||XZ 550 RK||14X|
|Engine||552 cc, 4-stroke, liquid-cooled, 70° V-twin two-cylinder, DOHC, 4 valves per cylinder||398 cc, 4-stroke, liquid-cooled, 70° V-twin two-cylinder, DOHC, 4 valves per cylinder|
|Bore Stroke:||80.0 x 55.0 mm||73.0 x 47.6 mm|
|Fuel System:||Dual Mikuni BD34, downdraft carburetors||Dual Mikuni BD36, downdraft carburetors||Dual Mikuni BD34, downdraft carburetors|
|Ignition:||TCI (Transistor Controlled Ignition)|
|Transmission:||5-speed, constant mesh|
|Overall Length:||2120 mm (83.5 in)||2145 mm (84.4 in)|
|Overall Width:||845 mm (33.3 in)||750 mm (29.5 in)|
|Overall Height:||1110 mm (43.7 in)||1090 mm (43.1 in)|
|Seat Height:||780 mm (30.7 in)|
|Wheelbase:||1445 mm (56.9 in)||1455 mm (57.1 in)|
|Weight (wet):||212Kg (467 lbs)||215Kg (474 lbs)|
|Suspension Front:||Telescopic trailing axle fork|
|Brakes Front:||Single hydraulic disc||Dual hydraulic disc|
|Brakes Rear:||Drum (Mechanical linkage)|
|Tires Front:||90/90-18 51H||100/90-18 56H||100/90-18 51S|
|Tires Rear:||110/90-18 61H||110/90-18 61S|
|Fuel Tank Capacity:||17 liter (4.5 US gal)|
See also:List of Yamaha motorcycles
- ↑ [Yamaha OEM Parts catalog: http://www.yamaha-motor.com/sport/parts/home.aspx]
- ↑ Choate, Curt; John H Haynes. Yamaha Vision Owners Workshop Manual. California, USA: Haynes Publications, Inc.. ISBN 1-85010-761-0.
- ↑ > (in English)XZ400 Supplementary Service Manual 14X-28197-20 to XZ550RJ Service Manual 16R-28197-60 (1st ed.). Japan: Yamaha Motor Co Ltd. p. 26.